Process for the production of liquid-fuel mixtures



' Dec. 29 ms. 1,567,

T. H. BUTLER ET AL PROCESS FOR THE PRODUCTION OF LIQUID FUEL MIXTURESFiled August 13, 1925 @VE/VTQQS We 12 M Patented Dec. 29, 1925.

UNITED STATES PATENT OFFICE.

THOMAS HOWARD BUTLER AND FREDERICK JAMES WILLIAM POPHAM, OF BRISTOL,

JOHN CHRISTOPHER MANN, OF BIRMINGHAM, AND HERBERT WILLIAM ROBIN- SON,CLEOBURY MORTIMER, ENGLAND.

PROCESS FOR THE PRODUCTION OF LIQUID-FUEL MIXTURES.

Application filed August 13, 1925. Serial No. 50,058.

To all whom it may concern! Be it known that we, THOMAS HOWARD BUTLER,FREDERICK JAMES WILLIAM Por- HAM,.JOHN CHRISTOPHER MANN, and HER- BERTWILLIAM ROBINSON, British subjects, and residents of Bristol, England,Birmingham, England, and Cleobury Mortimer, England, have invented acertain new and useful Improved Process for the Production ofLiquid-Fuel Mixtures, of which the following is a specification.

This invention relates to the production of liquid fuels by blendingcoal tar pitch with fuel oils of petroleum or asphaltic origin. The fuelvalue of pitch has been, of course, already recognized, and attemptshave been made to blend pitch with fuel oils such as petroleum.

When pitch is blended with fuel oil of the above kinds, there is atendency for the bitumen to separate out and to carry with it the freecarbon. It is the object of the present invention to produce pitch andfuel oil mixtures in such a condition that they may be employed asliquid fuels while maintained at a temperature above the melting pointof the pitch.

According to the present invention, the pitch to be blended with thefuel oil has its tem erature raised and maintained substantia y aboveits melting point, and the fuel oil is slowly stirred in. The pitch maybe melted and its temperature raised to the requisite point or the pitchmay berun direct from the stills wherein it is produced and thetemperature maintained at the necessary point. In the case of mostpitches the temperature may be raised to from 170 to 200 0., and shouldnot be allowed to fall below 150 C. The stirring is continuous but notnecessarily vigorous. The necessary temperature may be maintained eitherby the gentle application of heat to the vessel in which the pitch ismelted, or by pre-heating the fuel oil before stirring it into thepitch. The stirring should be more vigorous if the oil is added morerapidly, but there is generally no difiiculty in effecting the mixing.Too high a temperature must not be employed at this stage as there is aliability for the free carbon to be deposited from the pitch. It isfound that the critical temperature above which the blending must becarried out varies with qualities of pitch of difof pumping is soregulated that any desired amounts are tapped off from the pipe circuitby branches leading to burner nozzles, and yet leaving a certain amountof the mixture to be returned by the circuit to the melting and blendingvessel, as mentioned above, thus maintaining a continuous cycle.

Some embodiments of the present invention will now be described withreference to the accompanying'drawings, wherein 2- Figure 1 is adiagrammatic side elevation of the blending vessel, the pipe circuit andthe associated equipment; while V Figure 2 is a plan of the same.

In these drawings, A is the meltin and blending vessel mounted inbrickwofl: for heating by means of a. fire-grate F with side flues G. Apair of reversed cones B forming an agitating mechanism are mounted on avertical spindle C, and rotated from a driving shaft D through bevelgearing. The hot pitch from the stills enters through the pipe H, andthe fuel oil is admitted by way of the inlet pipe J'. There is a manholeE provided in the cover of the vessel A, so that cold pitch maybecharged in if necessary. The heated and blended mixture may be taken offby means of a pipe K extending down to the bottom of the vessel A, themixture being drawn in to the pipe K by a reciprocating suction mediumpitch and one ton of black fuel oil are admitted to the vessel A. Thepitch has, for example, a' melting point of from 72 to 80 C, and theblack oil may be a thick oil of asphaltic origin havin a specificgravity of from .950 to .980. uch an oil is a thick viscous oil having aviscosity (Redwood at 60 C.) of 292 and a flash point of 205 C. Thepitch is heated to 200 C. and the fuel oil steadily added through thepipe J. The fire on the grate F is continued and care taken that thetemperature does not fall below 150 C. The stirring cones B are kept inrotation and a mixture homogeneous above 150 C is obtained. On coolingbelow this, bituminous matter separates out, but is easily stirred inagain on warming. The pipe circuit M, 0 may be of any length, dependingupon the rate of pumping to ensure the return of a portion of the hotmixture to the vessel or tank A. To prevent heat radiation losses, thepipe circuit may be insulated, or alternatively, the temperature.maintained by means of an internal steam pipe or an external steamjacket.

The same apparatus and a similar process is employed for differentgrades of pitch and different fuel oils, and for blending mixtures ofdifferent proportions of pitch and oil, the only difference being thatdifferent temperatures may be employed under the different conditions.

The following examples may be cited: If the medium pitch, referredtoabove, obtained from mixed gas tar is used, and the same viscous blackoil, but two parts by weight of the pitch being employed with one partby weight of the black oil, the critical temperature above which theblending should take place, is still 150 C. If the proportions arealtered to three parts by weight of the same pitch to one part by weightof the same black oil, the critical temperature above which the blendingmust take place is reduced to 90 C.

In the case of a hard English pitch, obtained mainly from verticalretort tar and having a melting point slightly above 100 C, three partsby weight of this pitch may be blended with one part by weight of thesame viscous black oil, but the critical temperature above which theblending, must take place is then as high as 250 C. If hardpitch,similar to that just mentioned is employed, it. may be blended with alight fuel oil. Such an oil may be a thin oil of petroleum origin,having a specific gravity of .855, a viscosity (Redwood at 21 C) of 50,and a flash point of approximately 93 C. With such an oil, good mixturesare obtained which have low viscosity and are consequently readilymanipulated. If three parts by weight of the hard pitch, referred toabove, are blended with one part of this blending.

According to another exampde, soft American pitch, obtained from cokeoven tar and having a melting point of 60 to C., may be blended with thethin petroleum oil above referred to. If three parts by weight of suchsoft pitch is blended with two parts by weight of the thin fuel oil, thecritical temperature which mustbe exceeded is 120 C. If, on the otherhand, four parts by weight of the soft pitch of the above quality isblended with one part of the thin fuel oil, it is only necessary toblend above a critical temperature of 80 C. 7

According to yet another example, a medium pitch from American cokeovens, and having a melting point from 72 to 80 0., is blended with theabove-mentioned thin petroleum oil. If three parts by weight of suchmedium pitch be blended with two parts by weight of the thin fuel oil,blending must be carried out above a critical tem perature of 110 C. Inthis process, free carbon is found to separate out, if the temperatureof blending exceeds 300 C. and,

of course, this should be avoided.

It will be understood that the above are merely examples of certaingrades of pitches which may be employed, and certain fuel oils, and alsoof certain proportions of each of the two ingredients which are blended.It will be understood, of course, that the invention is not limited tothese examples, but briefly the invention may be said to consist inproducing homogeneous mixtures of pitch and etroleum residue by blendingthese constituents above a certain temperature, herein referred to asthe critical te perature, below which a bituminous aterial begins toseparate out and agglomerate. Generally speaking, this criticaltemperature may be lowered by either the use of a softer pitch or byincreasing the proportion of pitch'relatively to the fuel oil or finallyby the addition of solid hydrocarbons of the naphthalene or anthraceneseries, obtained from the distillation of coal tar.

Having thus described our invention, what we claim as new and desire tosecure by Letters Patent is 1.- A process for obtaining homogeneousmixtures of pitch and petroleum .residue which consists in melting thepitch, raising the latter to a temperature substantially above itsmelting point, and gradually admitting the petroleum residue whilecontinuously stirring.

2. A method of supplying fuel to liquid fuel burners,'consisting inblending pitch and liquid petroleum residue at a temperaturesubstantially above the melting point of the pitch, circulating saidblended mixture at a rate in excess of that at which the mixture isconsumed in the burners, and reperature of the molten mass bycontinuously 10 turning the excess of the mixture to a vessel heatingsame during blending.

' for reheating. I a In witness whereof we hereunto subscribe 3. A.method of producing a homogeneous our names this 31st day of July, 1925.5 liquid fuel which consists in raising the H MA H WARD BUTLER.

pitch considerably above its melting point, F E ER K JAMES WILLIAMPOPHAM. gradually adding liquid petroleum residue, Signed this 7th dayof July, 1925. and a hydrocarbon of the naphthalene or RB T W LLlAMROBINSON.

anthracene series, and maintaining the tem- N HRI T PHER MANN.

